The present invention relates to industrial stringlights. Stringlights are used in a wide variety of applications, such as construction sites and large scale manufacturing locations to provide temporary lighting or lighting which may be reconfigured.
For industrial applications, it is highly desirable that stringlights be capable of withstanding the rigors of use, particularly at sites such as construction locations or large scale manufacturing plants. Stringlights are frequently moved or they may be bumped by workers or struck inadvertently by objects being carried.
In addition, it is very important that the stringlight assembly be efficient and economical to manufacture, despite the high requirements for ruggedness and quality necessary for industrial applications.
The markets served by stringlights, particularly in the mid-range, requires an economical product, yet one which is suitable for the fairly harsh environments that are typically encountered.
The present invention provides an industrial molded stringlight including a screw-shell sub-assembly which includes a screw-shell body adapted to receive a wide range of conventional, incandescent lamps. A cap cooperates with the screw-shell body to define a plurality of channels for respective insulated wire conductors.
Insulation-piercing contacts are assembled to the screw-shell. The contacts may include a hot contact, a neutral contact and, if desired, a ground contact. The hot and neutral contacts are designed to be mechanically polarized. By this it is meant that the two contacts cannot be interchanged in assembly to the screw-shell, which, if it were permitted to occur, might create a hazardous condition. Further, the invention contemplates that the ground contact and the associated ground wire are optional without change to the screw-shell or other structure or to the molding process or the molds.
The cap which defines the upper portion of the wire channels, includes a peripheral lip which fits over a corresponding rim on the top of the screw-shell. When the lip of the cap is forced over the rim of the screw-shell, the two are positively coupled together in a manner which firmly engages the wires and causes a reliable piercing of the wire insulation by the contacts, thereby establishing electrical continuity between each wire and its associated contact element. Provision is made in the screw-shell for cavities to receive the insulation of the wire which has been displaced in the assembly/insulation-piercing operation. The tight engagement of the wires by the cap and screw-shell creates a secure, reliable mechanical assembly.
Each contact element, by virtue of its design, has a unique association with the screw-shell so that they may not be mistakenly placed in the wrong location. Moreover, the ground contact includes a peripheral ring received about the outer surface of the screw-shell, and the screw-shell contains a pair of peripheral, axially extended ribs which are spaced to receive the contact element for the ground contact, thereby ensuring proper location of the ground contact relative to the screw-shell, and establishing proper location and orientation of the insulation-piercing point of the ground contact for proper electrical continuity with the ground wire, if one is used.
Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed disclosure of the illustrated embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views.